Bletchley Park to rebuild pioneering EDSAC computer
Will omit deadly 1940s mercury-based memory
Bletchley Park is to rebuild one of the world's first modern computers.
The Electronic Delay Storage Automatic Calculator (EDSAC) was put together at Cambridge University in the late 1940s as a tool for researchers and scientists. The room-sized valve-based system, designed and developed by the late Sir Maurice Wilkes, first ran in 1949 and served academics faithfully for nine years until its decommission in 1958.
The National Museum of Computing at Bletchley is honouring the memory of the pioneering computer with a rebuild project, expected to last around three years. Visitors to the museum will be able to see the painstaking work in progress.
The UK's Computer Conservation Society (CCS) commissioned the rebuild and has put together a budget of £250,000 to finance the project. Computing entrepreneur Hermann Hauser led the consortium that coordinated the fundraising effort.
Early phases of the project will involve going through archives and interviewing engineers who worked on EDSAC to get a better idea of how the machine functioned. The project is complicated by the fact that few parts of the original valve-based calculating machine remain intact.
"We're building up a good picture of what it was like," said Dr David Hartley, chairman of the CCS, told the BBC. "But there comes a point at which we have to guess what was in the designer's mind at the time."
Modern health and safety regulations mean that one component of the original machine, 1.5m long tubes of mercury used as a memory store, cannot be used. Scientists plan to carry out experiments to determine a suitable "delay line" memory replacement.
This workaround aside, the computer scientists are going out of their way to remain as faithful as possible to the original design.
The original had over 3000 electronic tubes used for logic, data input via paper tape and output on a teleprinter, as well as the now safety-violating mercury-filled tubes for memory, a statement on the project by the National Museum of Computing explains.
Professor Andrew Hopper, head of the computer laboratory at Cambridge University, explained: "EDSAC set computing standards for academia and commerce. It was so successful that in the nine years following 1949 it was used by Cambridge University researchers in studies such as genetics, meteorology and X-ray crystallography and even helped two researchers win Nobel prizes.
"EDSAC also led directly to the first commercially applied computer, the LEO, that broke new ground by enabling the catering company J Lyons & Co Ltd to perform payroll calculations in 1953."
The EDSAC rebuild project follows the successful rebuild of the Manchester Mark I and Colossus computers. ®
The paranoia over the dangers of mercury is now out of hand.
The paranoia over the dangers of mercury is now out of hand. That it can't be used at Bletchley Park to recreate something as special as the storage delay simply borders on the hysterically absurd. Even if the new bogeyman is mercury, there's no reason why special precautions and enclosures cannot be used to make it environmentally acceptable. It seems to me there's very little point in recreating this computer if this not authentic. Why bother at all? May as well make it out of plasticine if it isn't done correctly.
In the lax days of a few decades ago when there was almost no regulation over mercury, it was used in large quantities in industry and one rarely heard of anyone getting mercury poisoning. If you walked into a railway rectifier room of about 40 years ago, you'd see gallons of it inside huge mercury-arc rectifiers all glowing with an eerie violet glow. One never heard of utter disaster when one broke (which they occasionally did). Whenever I entered a Hg-arc room (an occasional experience), I was always much more concerned about the high voltage than being poisoned by the Hg.
Sure, this element in metallic form can be dangerous if not handled correctly but handling it is now well understood. Moreover, professions that were reckless with it had long since gone by the end of the 19th C. (Making Daguerreotype photos whilst breathing volatile Hg fumes, or being a 'mad' hatter and curing pelts with Hg were professions seemingly devoid of even the most elementary precautions.)
Metallic mercury isn't that dangerous if handled with care, and I've a mouthful of mercury amalgam fillings to prove it, some of which I've had for many decades--yet I'm still sufficiently compos mentis to write this. ;-) Remember too, if you'd caught syphilis before the War then you'd have little choice other than to ingest mercury. With luck, and if you'd successfully managed the thin line between Hg OD and an insufficient amount, then it might have eventually cured you.
Mercury is still used in the form of thimerosal as a preservative for vaccines; we think its toxicity is sufficiently low that its use outweighs the perishing of vaccines. Until recently, the antiseptic Mercurochrome was commonly available (and I still have a bottle of it).
When I was at high school, we had large jars of mercury and one of the most memorable experiments was to try and push one's hand to the bottom of the jar (Hg about 10cm deep). It's is quite a challenge I can assure you. (We did it outside and scrubbing with soap afterwards was the order of the day.)
That said, some organic compounds of mercury are very dangerous, specifically the (mono) methylmercury cation, CH3Hg+, and its very nasty and extremely toxic brother, dimethylmercury (CH3)2Hg. Monomethylmercury+ is of concern because in this organic form it can enter the food chain and become a cumulative neurotoxin. This happened about 50 years ago in Minamata Bay in Japan with horrific consequences for the local fish-eating population. The Hg entered the bay as effluent in the CH3Hg form 'dumped' by an irresponsible industry.
(BTW, Those whose chemistry has not deserted them completely will know that if you're using metallic mercury in some industrial process it won't suddenly start producing organic forms and become super toxic (unless that process is a specialised chemical one). If you're careless, you might suffer the effects of the metallic mercury, but in the event you were tested and found to ALSO have traces of CH3Hg in your system then it almost certainly won't have come from your exposure to the metallic form. Almost certainly, it'll have come from top-predator fish that you've been eating. Outside the lab, CH3Hg is usually produced when microbes convert metallic Hg to the very dangerous organic form which fish accumulate.)
Perhaps I've written an overly long rave but I've done so because I'm becoming increasingly concerned about how timid and overprotected our society has become in recent years. Not only are we producing a society full of people who are terrified of anything 'chemical' but also the hands-off approach to chemicals is deskilling the nation. I now know people who have never seen liquid mercury in their life, and who are terrified of the thought of coming across any. Ban it from schools and this is what happens. It's tragic really, it's no wonder Asia, without such hang-ups, is wiping the floor with us.
We never seem to get regulations with the correct balance. With respect to hazardous chemicals, we've gone from having almost no regulations 50 years ago to the other extreme where we can't even use mercury in this historic Bletchley Park computer. It's just crazy, much of the blame has to be leveled at the damn postmodernists who infiltrated our education system some 20/30 years ago and subverted it with anti-science rhetoric. Now we've a large core of the population who are deeply suspicions of science.
Finally, my position is not for tight but rather sophisticated regulation. For instance, I'd greatly tighten the regulations for handling mercury in schools than from the time when I was there but in no way would I ban it. Otherwise, how else are kids ever going to get experience when there's nothing to get hands-on experience with.
[Oh, BTW, at school we even had samples of metallic uranium and its ore as well as alpha and beta radioactive sources that we used for proper hands-on experiments (such as the different blocking properties of various materials when exposed to alpha particles). Being the school's electronic nerd, I even built my own Geiger-Müller counter. If I hadn't had access to these radioactive sources then there's no way I would have tackled such a project. At 14, it felt like a great achievement. For kids, hands-on, messy, noisy science is essential; theory is just not sufficient.]
We used to roll balls of mercury up and down the desks of the science lab at school and it hasn't effected wibble wibble zxoop
Going to be faster...
than any modern machine running vista.